THE WORLD: Terrorism; With Latest Bomb, I.R.A. Injures Its Own Cause

By HOWELL RAINES

Published: November 15, 1987

BELFAST—
THE Irish Republican Army rarely second guesses itself about the violent attacks that have claimed hundreds of lives in Northern Ireland in the last 17 years. But after one of its bombs killed 11 people at a memorial service for veterans in Enniskillen last Sunday, the outlawed organization issued its second apology in five years.

The last one came in 1983 when five people died in what the I.R.A. leadership called an unauthorized attack on Harrods department store in London. This time, the I.R.A. blamed the ''catastrophic consequences'' at Remembrance Day in Enniskillen on the accidental detonation among civilians of a bomb intended for its preferred targets, British army troops and the Royal Ulster Constabulary. British and Irish officials alike denounced the apology as insincere and twisted in its logic.

''These rats are now scurrying for cover in the sewers of their own violence,'' said Alan Dukes, leader of the opposition Fine Gael party in Dublin. Indeed, the I.R.A. apology seemed to have more to do with public relations than remorse. Leaders of the I.R.A. and its political wing, Sinn Fein, recognize that attacks on civilians undermine political support and international sympathy for their campaign to re-unite Britain's six-county province of Northern Ireland with the rest of Ireland.

''Given the fact that the I.R.A. have made terrific ground in this last year, the incident that occurred Sunday was a devastating blow . . . a major setback,'' said Jackie Donnally, a spokesman for Sinn Fein in Belfast.

An unnamed person identified as a senior I.R.A. leader, in an interview with the Independent, a London newspaper, used similar language, saying that while hard-core support in the Roman Catholic areas of Northern Ireland remains solid, the I.R.A.'s standing among sympathizers north and south of the border and with its international support system in the United States and elsewhere would be ''just totally devastated.''

While I.R.A. supporters normally distrust British newspapers, the organization's own weekly, ''Republican News,'' said the bombing was a '' monumental error,'' that would strengthen the I.R.A.'s opponents. Losses of Men and Arms

Virtually no one agrees with Mr. Donnally's assertion that 1987 has been a good year for the I.R.A. Fifteen of its men have died this year, as compared with five in each of the two previous years. Two weeks ago, the I.R.A. lost its biggest arms shipment ever when the coastal ship Eksund was seized in France with 150 tons of weapons and ammunition.

Earlier this year in its first attempt to win and occupy seats in the Republic of Ireland parliament, Sinn Fein got only 1.9 percent of the vote in a country to which Northern Ireland's Roman Catholic minority looks for support.

It has been a bad year, too, for the I.R.A. in its propaganda battle with the British Government. Events such as Enniskillen enable the British to depict the I.R.A. and offshoots such as the Irish National Liberation Army as terrorists, rather than as the freedom-fighting heirs of the movement that joined battle against British control of Ireland in the Easter Rising in Dublin in 1916, an event that moved William Butler Yeats to write of the emerging nation: ''A terrible beauty is born.''

''Their life is full of miscalculation in political terms,'' said a British official in outlining Prime Minister Margaret Thatcher's plans to sustain the political advantage flowing from the Enniskillen bombing. She is pressing the Irish Prime Minister, Charles Haughey, to support ratification of a new treaty on extradition of terrorists between Ireland and Britain.

Because of traditional Irish suspicions about the British courts, it was expected that Mr. Haughey could delay action when the matter comes before parliament on Dec. 1. Now a powerful opposition coalition is demanding passage.

Mrs. Thatcher has told associates that she will not go along with punitive demands from unionists, such as preventive detention for suspected terrorists, on the grounds that severe repressive measures could swing public opinion back toward the nationalists. Mrs. Thatcher wants to maintain the advantage that the bombers handed her in what Tim Pat Coogan, author of the book ''The I.R.A.,'' calls Northern Ireland's ''politics of the last atrocity.''

Outrage over Enniskillen, for the moment, has shifted attention away from such Catholic grievances as an unemployment rate in Northern Ireland, which is two times higher for them than the rate for Protestants. The Protestants outnumber the Catholics in the province, by about 900,000 to 600,000. In the Irish Republic, 94 percent of the people are Catholics.

Also, attacks on Catholics by Protestant paramilitary groups are receiving little publicity. So far this week, six Catholics have been wounded by gunfire in Belfast, and security officials warn that the Protestant groups may attempt reprisal bombings in southern Ireland. 'This Pathetic Excuse'

Officials on both sides of the border were on guard over the weekend for renewed violence, since today marks the second anniversary of the Anglo-Irish Agreement, under which London and Dublin are supposed to cooperate to find middle-ground solutions to Northern Ireland's problems. It is opposed by hard-core unionists and nationalists as a threat to their desire to dominate the politics of the province for their separate purposes.

Over the years, nationalists have condemned Protestant assassination squads as random killers and portrayed the I.R.A. as taking care to spare bystanders while aiming selective strikes at the security forces and government officials it regards as foreign occupation forces. In its statement, the I.R.A. tried to preserve that image of itself by saying that the Enniskillen bomb killed civilians because it was triggered at an inopportune moment ''by the British Army scanning high frequencies'' with electronic bomb detectors. What a British official called ''this pathetic excuse'' was greeted with a flood of condemnation in London and Dublin.

This exchange illustrates the grimly metaphysical tone of the debates about death in a place that tries to distinguish between justified and unjustified political killings. Meanwhile the statistics mount with an irrefutable authority of their own. Eighty-seven people have died this year on all sides, 52 of them killed by the I.R.A. Since the present cycle of violence began in 1969, the I.R.A. and other republican groups have killed 1,499 people, including a number of their own group done in by feuds or bomb accidents. The Protestant paramilitary groups have killed 659, and the security forces have killed 297.

Politics aside, these figures document what Mr. Coogan, the author, calls an ''Anglo-Irish dance of death,'' and last week, once again, it was hard to argue that such language exaggerates the reality of Ulster.